We will develop compact and efficient diode-pumped fiber lasers for the surgical treatment of otologic diseases, with particular emphasis on instruments for performing stapedotomy. The fiber lasers will be designed to meet the critical requirements for inner-ear laser-surgical procedures - optimal tissue ablation with minimal thermal, acoustic, and vibratory effects. The otologic laser will emit at the 2.8 mu m - 2.9 mu m range,coinciding with the strong water-tissue absorption band. We will leverage the experience and successes of the closely collaborating University of New Mexico (UNM) team towards the development of high power (>10 W, variable pulse energies in the range 1 mJ - 100 mJ) diode-pumped 3 mu m fiber lasers using double-clad, large.mode-area fiber geometries, and the Er, Er/Pr, and Ho/Pr fluoride fiber material systems. The knowledge gained in the development of the breadboard- type fiber lasers in Phase I of the program will be used for the construction of prototypable fiber lasers with microendoscopic beam delivery systems for the animal studies (cadaveric rabbit and live rat models) that will be pursued in Phase II. For this phase of the project, the use of mid-IR fiber lasers for stapedotomy will be investigated through a series of experiments that will explore critical issues such as perlymph heating, acoustic shock effects, and tissue ablation properties of the laser. Such studies will elucidate the issues leading to commercializable ultra-compact laser instruments optimized for otologic surgery. PROPOSED COMMERCIAL APPLICATIONS: Medical Application: Dermatology, Ophthalmology, Cardiology, Dentistry. Nonmedical Applications: Plastics machining, Pollution monitoring, Semiconductor process monitoring